Modern vehicles are being equipped increasingly with autonomous driving (AD) systems. Operation of these systems is improved with accuracy of vehicle and environmental data available.
Advanced AD systems use data including road grade angle and vehicle pitch angle, especially in acceleration, deceleration, and/or sloped-road situations.
Road grade angle and vehicle pitch angle can be measured, directly. The angles can be measured, for instance, using one or more dedicated optical sensors, and/or a multi-antenna satellite arrangement—e.g., Global Positioning System (GPS). A high-accuracy GPS unit can be placed at each of four corners of a vehicle to measure pitch (also, roll and/or yaw) angles of the vehicle. These methods are very expensive, though, and not feasible within typical consumer price points.
Moreover, measurement data may have inaccuracies due to even slight measurement-device offset or error, noise, and/or failure of the system to still contextualize the measured data—e.g., even if pitch-direction movement is accurately detected using GPS units, the system would require accurate road-grade angle data in order to properly determine what proportion of the measured pitch-direction movement is due to vehicle pitch as opposed to road grade.
The present technology solves these and other shortcomings by estimating accurately both vehicle pitch angle and road grade angle, together, using a correcting observer software module applying a tuned observer gain.